1Department of Neurology, Akershus University Hospital, PO Box 1000, 1478 Lørenskog, Norway
2Department of General Practice, University of Oslo, Oslo, Norway
3Department of Neurology, Oslo University Hospital, Oslo, Norway
4The Norwegian Air Ambulance Foundation, Oslo, Norway
5Department of Neurology, Haukeland University Hospital, Bergen, Norway
6National Headache Knowledge Center, Rigshospitalet, Copenhagen, Denmark
7Department of Research, Innovation and Education, Division of Clinical Neuroscience, Oslo University Hospital, Oslo, Norway
8Danish Headache Center, Glostrup – University of Copenhagen, Copenhagen, Denmark
© The Author(s) 2020
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